McConnell S J
J Pineal Res. 1986;3(2):119-25. doi: 10.1111/j.1600-079x.1986.tb00734.x.
The circadian plasma melatonin profile of a marsupial, the tammar, was determined at various stages of the annual reproductive cycle. At 6-14 days after each of the solstices and equinoxes, six females were exposed to a photoperiod equivalent to the natural day length at these times. Serial blood samples were taken 8 days later at 2-4-hourly intervals, and plasma melatonin concentrations were measured by radioimmunoassay. Melatonin concentrations were elevated during the dark phase of each photoperiod, and there were significant changes between the profiles in each season. The amplitude of the nocturnal rise was significantly higher (P less than 0.05) during the breeding season after the summer solstice (peak 259.5 +/- 26.8 pg/ml, mean +/- SEM) and autumnal equinox (287 +/- 53.2 pg/ml) compared to those during the nonbreeding season after the winter solstice (111.5 +/- 10.5 pg/ml) and vernal equinox (154.5 +/- 10.4 pg/ml). The duration of the nocturnal rise was significantly correlated (r=0.996, P less than 0.01) with the length of the dark phase and so was shortest after the summer solstice and longest after the winter solstice. Either of these changes in amplitude or duration might provide the photoperiodic information that regulates the annual reproductive cycle of the tammar.
在有袋动物帚尾袋鼩一年生殖周期的不同阶段，测定了其血浆褪黑素的昼夜变化情况。在冬至、夏至和春秋分之后的6 - 14天，让6只雌性帚尾袋鼩暴露于与这些时间自然日照长度相当的光周期下。8天后，每隔2 - 4小时采集系列血样，采用放射免疫分析法测定血浆褪黑素浓度。在每个光周期的黑暗阶段，褪黑素浓度都会升高，而且每个季节的变化情况之间存在显著差异。与冬至（111.5±10.5 pg/ml）和春分（154.5±10.4 pg/ml）之后的非繁殖季节相比，夏至（峰值259.5±26.8 pg/ml）和秋分（287±53.2 pg/ml）之后繁殖季节夜间升高的幅度显著更高（P<0.05）。夜间升高的持续时间与黑暗阶段的长度显著相关（r = 0.996，P<0.01），所以在夏至后最短，在冬至后最长。幅度或持续时间的这些变化中的任何一个都可能提供调节帚尾袋鼩年度生殖周期的光周期信息。
